From what I can see, I think am looking at a Raleigh bottom bracket. If so 26 threads per inch, not the standard 24. Not sure when raleigh changed to 24 TPI. The left cup is r hand thread, the one on the chainwheel side is left hand, and fixed by being screwed in tight. You can easily remove the adjustable cup on the left side, just release the locking ring, gently tap it with small chisel if nothing else, or correctly with a C spanner. Inside you should find 11 1/4 inch balls each side.
You appear to have a mass produced raleigh (about 1000 complete bikes a week) made in the Carlton factory. These were sold under a variety of names , Sun, BSA etc. If it has the steel saddle pillar then it is the same tubing used to produce raleigh roadsters. All this is well documented.
I hope this helps.